AST1002 ch11-14

Q: What are the two gas giants?

A: Jupiter and Saturn — primarily hydrogen and helium with metallic hydrogen cores.

Q: What are the two ice giants?

A: Uranus and Neptune — contain more ices like methane, ammonia, and water.

Q: Why do Jupiter and Saturn appear flattened?

A: Rapid rotation causes oblateness.

Q: What is metallic hydrogen?

A: A state of hydrogen found inside Jupiter and Saturn that behaves like a metal and conducts electricity.

Q: Why do Jupiter and Saturn radiate more heat than they receive from the Sun?

A: They generate internal heat due to slow gravitational contraction.

Q: What causes the blue appearance of Uranus and Neptune?

A: Methane absorbs red light and reflects blue.

Q: What is differential rotation?

A: When a planet rotates at different speeds at the equator vs. the poles.

Q: Which giant planets have rings?

A: All four — Saturn (most visible), Jupiter, Uranus, Neptune.

Q: What is tidal heating?

A: The flexing of a moon due to gravitational forces, creating internal heat (e.g., Io).

Q: What moon is most volcanically active?

A: Io (Jupiter's moon).

Q: Which moon is a top candidate for life due to its subsurface ocean?

A: Europa (Jupiter) — ocean beneath icy crust.

Q: What makes Enceladus interesting for astrobiology?

A: Ice geysers suggest a subsurface ocean.

Q: Which moon has lakes of methane and a thick nitrogen atmosphere?

A: Titan (Saturn).

Q: What is the Roche limit?

A: The distance within which a moon would be torn apart by a planet's gravity.

Q: What is cryovolcanism?

A: "Cold" volcanism — eruptions of water, methane, or ammonia instead of lava.

Q: What is resonance in moon orbits?

A: When two moons orbit in a simple ratio (like 2:1), leading to gravitational interactions.

Q: What is a meteoroid?

A: A space rock moving through the solar system.

Q: What is a meteor?

A: A meteoroid that enters Earth's atmosphere (creates a streak of light).

Q: What is a meteorite?

A: A meteor that survives the atmosphere and hits Earth's surface.

Q: What causes a comet's tail?

A: Solar radiation vaporizes material from the nucleus when the comet nears the Sun.

Q: What are the parts of a comet?

A: Nucleus, coma, ion tail (blue), dust tail (white).

Q: Where do most comets come from?

A: Kuiper Belt and Oort Cloud.

Q: What are NEOs (Near-Earth Objects)?

A: Asteroids or comets that come within 1.3 AU of Earth's orbit.

Q: Why are rubble-pile asteroids a problem for planetary defense?

A: They're loosely bound, so nuking them may scatter rather than deflect them.

Q: What happened during the Tunguska event?

A: In 1908, an asteroid exploded in the air over Siberia, flattening 1,000 square miles.

Q: What is the nebular hypothesis?

A: The solar system formed from a rotating disk of gas and dust.

Q: What is accretion?

A: Process of small particles sticking together to form planetesimals.

Q: What is differentiation?

A: Separation of materials in a planet or asteroid into core, mantle, and crust by density.

Q: What are stony meteorites?

A: The most common type; made mostly of rock.

Q: What are iron meteorites?

A: Made from the core of differentiated asteroids; very dense.

Q: What are stony-iron meteorites (pallasites)?

A: Rarest type, containing both rock and metal; very valuable.

Q: What is a carbonaceous chondrite?

A: A meteorite rich in organic material and amino acids.

Q: What is radiometric dating?

A: Using decay of isotopes to determine the age of rocks; oldest meteorites = 4.6 billion years.

Q: What is panspermia?

A: The idea that life on Earth may have originated from microbes delivered by meteorites (especially from Mars).

Q: Why do scientists think some meteorites come from Mars?

A: Chemistry matches Mars and some contain possible fossilized microbes.